P0011 and P0299

Hi everyone and thanks for your help in advance
I'm not sure if I'm posting in the correct location. If not I apologise and directions to the correct location would be appreciated.
I recently bought an Audi A4 Avant 2.0 tfsi 2005 with 117000 on the clock.
Had the cam belt and water pump changed immediately for an eye watering £600! That was about 2 months ago. Yesterday the engine management light came on. I took it for a diagnostic test and the following fault codes appeared
P0011 - Camshaft A timing o early or system fault - camshaft timing !Removed! Bank 1 target valve not attained
P0299 - boost pressure below control limit
The mechanic advised to change the cam sensor, however, he said the ssue was likely that the camshafts needed to be replaced. He said this was likely to cost between £600 and £800. My question is before I cancel Christmas and remortgage the house is the issue likely to be less severe? I've read a lot on various forums and people have been discussing different things from oil filter changes to timing belt tensioner being dodgy. Unfortunately very few threads lead to a consistent resolution. Although none seemed to suggest completely replacing the camshafts. As you can tell I'm not a mechanic or even remotely technical when it comes to cars so any help or advice would be greatly appreciated and wellreceived!