First photocopy the receipt (see below)
Take it back to fitting garage they should sort it free of charge. if they wont take it to a FORD garage tell them they will check if new cat was fitted. seems to me it may be either loose wire or old cat bodge repaired. Get a six foot male friend built like a house to take it back they wont refuse his demands. In any argument with the garage only offer photo copy of original receipt if they ask for it.
Always keep original receipts in arguments with retailers. Give them photocopies only unless you satisfied with exchange or refund. trading standards are also helpful.
bob uk
July 2014
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