having the same resistence problems here too. Spoke to vet friend this morning who says the only thing thats working is 'Stronghold'.....you need a prescription unfortunatly. It kills fleas, flea eggs, ticks, worms and ear mites so worth the money. I have tried online this morning but cant find anyone who will supply without pre.
If you do use Frontline make sure it`s the Frontline Combo,don`t think it is available on line,but it is ace stuff. The ordinary plain Frontline seems not to work anymore..but Combo really does.