Audi *****s breed like rabbits
Without the boiler make/model it's like asking 'my car won't run for more than 2 seconds' You'll get answers like:
I have a Potterton Prima F from 1995 that did the same thing and it sort of got worse in the preceeding months. A quick check of the reset switch underneath showed that with some pressure (flexing the circuit board) the boiler would light. Google tracked this as a common fault with this circuit board so before shelling out Ł40 for a swap or Ł80 for a 'new' one, it was out with the soldering iron to freshen up the joints underneath. That was six months ago and the boilers worked every time since.
Hope the engineer's visit is/was OK.
Derren Brown (no, not really)