Thank you all for replying.

A few of you mentioned it may be a fuse, but I was assuming that front and rear wipers would use the same fuse? However I will check it just to rule that out.

I hear what your all saying, I just got off the phone to my ford dealer, they quoted me £520 for a alternator plus fitting, I'm going just get it done and hopefully all will be well.

How would I know the difference between a decat and a remap? It's my second ST but i only had it a few weeks now and all I have is a reciept from the previous owner basically that says thanks for your custom, £200 remap. But somebody did say that could be whats causing it to give a fault code for the lamba sensor, but regardless I will follow all your advice and get the Alternator done and dusted first.

Thank you all for help, much appreciated.