If you want to keep the car, get the cylinder head de-coked, then get an Alfatune remap and DPF-EGR delete, as its the regenerations that burnt the carbon onto the exhaust valves in the first place and why there are redesigned valve seats as a result.
When mine had this problem AR UK authorised a new head be sourced, and the labour to remove the old one, but wanted their rep on site to agree to opening the box for the new one, they took one look at the old head and authorised fitting on the new.
I don't have the car anymore, but with the new head the regenerations slipped by unnoticed and the car never shuddered again.
In your case, as they are prepared to cover all the labour, belts etc. why don't you offer to contribute to the trade cost of a new head, that way you will have a properly sorted car and a great selling point to other Alfisti, OK, you pay for the head, but youre getting a free major cambelt service. - just a thought....a head is about £1000 trade.
Last edited by cj romeo; 19-07-13 at 07:39.