No i didnt check there ID i should of.
wowcher was £35 yes sounds cheap but i use wowcher alot for deals hotels days out etc and do save lots of money so didnt see me having a problem
Don't know the last time I was asked for mine, not many customers bother.
I take it Wowcher is like groupon, discounted rates to build customer base. These promotions are usually used by new businesses or franchise groups. If you have direct contact with the engineer you need to get him back to check he has not caused the issue and request documentation on visit completed.