That’s a bit rude, isn’t it!
Hi alfredo romeo (that a good cover name).
When I had my (former) 155 2,0 16v done it came to aprox. £ 75 for both belt, £ 50 - £ 70 for tension wheels (change if black, check for wear if white) and about 2,5 hours labour. If engine sounds like a diesel have the variator changed, I don’t know how much they are; some can be repaired – look at www.alfa155.co.uk where you find the diesel clatter sound track and a Service Bulletin on the various options for repair/replacements.
The issue have been discussed at length at the 155 lounge and alfa155.com.