what gaurantee do you have after a service?

Generally none in law - depends on the equipment - what service was done - who did it - what went wrong afterwards. For liability you have to show that the work done during the service actually caused the subsequent problem - the onus is on the complainer - drained the oil in the engine of a car but forgot to put any more in and engine seized - you still have to prove it was their negligence.

It sometimes helps to speak nicely to the people who did the service - they may want your return business and try and solve your problem even if they are not liable.

Good luck...

Peccavi
April 2010