There are a lot of things you can do. First of all, you probably want to stop trying to give baby the bottle yourself. :) Most breastfed babies will refuse if mama is anywhere nearby. Sometimes you have to be out of the house entirely before they will give in and drink.
Try lots of different bottle nipples. Silicone, or natural rubber. Sometimes the rubber has a softer feel. (Natursutten makes a good rubber nipple -- they treat the rubber to remove the protein that can make kids more sensitive to latex allergies.) Have the caregiver try a few things ... sometimes they need to make it as much like breastfeeding as possible. Skin-to-skin, snuggled up close, rocking in the rocking chair. Maybe even in a warm bath together (at least at first) for maximum relaxation.
But sometimes it needs to be as different from breastfeeding as possible. Hold baby in a more upright position, even facing away from papa all together so babe has things to look at in the room and distract from how different the feeding is. Try sitting baby in a bouncy seat even.
If the bottle-feeding fails (some babies just never really figure it out), there are options. Medela makes soft cup feeders (you just tip a few drops of milk into baby's mouth and they have a swallow reflex) and there are also finger feeders. The finger feeders are especially great. (fingerfeeder dot com) They're made for breastfed babies who need supplementing, but my son loved to suck on my husband's index finger (clean, fingernail down) and I suspect they would have worked well beyond those early days.
Our son didn't have to take a bottle early on (except for a few nights out here and there), so by 4-5 months, I started to introduce a sippy cup. We liked the Nuby straw sippy.
My son never really took more than 2 or 3 ounces at a time via bottle. Just have the caregiver offer often. I never subscribed to the "they'll figure it out when they get hungry enough" idea. It's not a matter of being hungry enough, it's about teaching them HOW to drink from a bottle when they don't understand how, and that it's OKAY to drink from one, even though it's so different from their favorite way to eat. Babies don't like change. :)