Hello everyone, just to let you know, we have just returned from a brilliant holiday in Turkey, whilst we were there I contacted Bayram who came and looked at our pool electrics. Sure enough, he found various errors with overloads and breakers rated far too high for the pump, so when they should have tripped they didn't hence the burn outs. There was a phase regulator fitted previously, but again this was faulty. Bayram replaced all the bits and sorted it out for a reasonable fee.
Thanks to you guys for the advice, hopefully that will save us a few quid going forward! Matt.