No tax invoice after multiple requests

Two weeks after having a laptop repaired at Ensure, and after multiple requests, via email & telephone, for a tax invoice - I still have not received it. After my second request they rep**** with an email saying I need to send the unit in for them to assess it - this is after the unit was already sent in, assessed, a quote sent & accepted, & payment made! The people who answer the phone barely speak English & can barely make themselves understood - I honestly don't know how this place does business!<br> I really don't understand what is so difficult about sending a tax invoice for a job completed - surely I'm not the first customer to ever make this request? Appalling service!