Day 3 after composite bonding. This is the 2nd time the same spot the bonding has chipped. Is it even worth having?

You may not be aware of your bite, but it is very likely that you are bruxing (grinding your teeth) at night. I suggest for starters that you return to your dentist, he evaluate your bite, redo the bonding and make you a night guard to protect your teeth and dentistry from the damaging effects of bruxing.Another alternative is discuss with your dentist the option of doing a porcelain veneer. Porcelain is stronger and should be much longer lasting than direct composite (plastic) fillings. The veneer will also cover the front surface of your tooth, thus giving it better retention and less likely to come off than composite bonding.

Although you claim it has nothing to do with your bite, it has EVERYTHING to do with your bite. Your dentist must carefully analyze your bite in ALL MOVEMENTS possible. You are probably bruxing in your sleep and weakening the bond.