aww you poor thing! I remember this happening with my friends son. So i took him for a day and told her that he would be on bottles by that night.
He screamed and wanted boobie till he got more and more hungry and just drank the bottle.
The reason I did it is because she couldn't nurse anymore and couldn't stand him crying. It was horrible. BUT i can listen to someone elses baby cry without it effecting me as bad. Maybe someone can take your son for the day?

I would try sticking with the same formula. It probably isn't the formula. I would also pick one bottle type (I use soothie bottles b/c the nipple is fat and resembles nursing). They also have pasifiers by soothie, you could get him to take that by putting the nipple at the roof of his mouth, be persistant, and then maybe trick him by substituting the bottle. I would also try a sippie cup if he will take it. I know it sounds crazy but my neice will not take a bottle with formula but takes it from a sippie cup just fine. You could try feeding him 30 minutes early or about 10 minutes late. Either extreme he might be a little thrown off and eat. But don't be mean about waiting for him to be really hungry. Within reason, try to give him the bottle when he is hungry. And pick a feeding he isn't really interested, like when he gets distracted the most. And try try try. I wouldn't try at night before bed, but I would try first thing in the morning and then at least one more time each day until he takes it. But beware. Sometimes babies will go on what they call a "hunger strike". Which basically means, they are stubborn and won't eat the formula and so they think they will get the breast. So if your baby refuses the bottle, don't go straight to whipping out your breast. I have a book that suggests the following it is called the baby whisperer by tracy hogg.
never force the bottle
try every hour the first day
let another person try, but only when you first introduce the bottle
expect and ride out a hunger strike
always give a bottle once a day or baby won't stay used to taking it
start with the first bottle of your baby's day when she is the hungriest
find a nipple type that resembles your own
So there are a few things from myself and an expert. I hope this helps good luck! I had to wean my baby from breast to formula at 2 months b/c she couldn't digest my milk, it wasn't easy but I did it.

Hi there,  I had a similar problem.  My son suffered from nipple confusion going from bottle to breast so my early childhood nurse recommended I use a Peristaltic Nipple (see attached link for more details).  Introducing formula to bub: mix half breast milk with half formula for a while so your baby gets used to the flavour slowly, then increase the formula amount until there is no breast milk in the mixture.  Good luck

www.pigeonbaby.com.au/premiumrange.htm

Aparently after 3 mths of age it is notoriously hard to introduce a bottle, more so with boys.  My girls have never had one so Im no help there. My 10.5 mth old goes to CC 2 days a week and she drinks her EBM out of a straw cup. BF babies (again apparently!) find straws easier to suck, I know my eldest did, she never mastered the sippy cup. D also drinks water from a sports bottle, she just chews on the sippy cup.

My eldest took a bottle without any dramas 9once a week so I could go to orchestra practice) but my youngest has always refused to drink breastmilk from anything other than me (I have never tried formula). I have tried teats of every colour shape and texture and I have tried other methods of feeding such as cups etc. It didn't work for me but perhaps since your baby is older you could try EBM or fomula from a sippy cup or a cup with a straw. Sometimes the bottle being sort of like the breast but not the real thing upsets babies. 

Hope this helps, not much comfort but my youngest still prefers to drink from me than anywhere else-sometimes getting him to drink water is a chore.

I tried as you did to wean my son at 9 months and many formulas and bottles later he still wouldn't. The only thing that worked was changing the temp. I gave him a bottle from the fridge one day and he actually took it (i nearly had a party). So maybe try cold bottles (or different temp from bm).

Gosh this brings back memories - and not all of them pleasant. i went back to work fulltime when my son was about 8 months old (it didn't last mind you...) but for a few months that was the situation and it absolutely did my head in. My son wouldn't drink ANYTHING except breastmilk. I'd leave formula, water and juice for him and he'd just wait for me to get home!!!!
And as anxious as it made me he never got seriously dehydrated. I never thought he'd take the bottle. So when I gave up breastfeeding at age 2, so when he really didn't need a bottle he took it up with a vengeance (normal milk) and is still on it at 3.5!!! So i guess what I'm saying is that: you can't force your child to drink. Make other alternatives available and if he is thirsty enough, he will drink. Nature will take over. And don't worry!!!