turbo intermitantly boosting and now loss of power

[ade82]

Hoping someone can help me, my A4 B6 1.8t Quattro runs with a KO4 and has been remapped. the turbo started to boost when its supposed to then sometimes would not. Now its off the road with no power after cutting out, when I lifted the bonnet there was a red ring around the cat converter after the turbo.

 After speaking to two garages one has told me the cats choked and the other has said its probably not, possibly just an earth fault or a remap problem. I've already spent £1100 through this fault in the last  10 weeks or so and not wanting to carry on spending needlessly

[James]

What have you tried so far in spending the £1100 on?

[ade82]

The garage changed a faulty sensor,the alternator packed in while it was there, fuel pump went,few things all at once but pricey parts. The cat after the turbo went red hot somehow,wondering if cause it's remapped that's there's a problem with over fueling and it's choked

[James]

Has it been scanned for fault codes?