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Thank you chaps for all your help.
Firstly, I asked a copper (who is high up in the force) for his advice (as a hairdresser I meet alsorts!) basically he said it is difficult to prove, which I have to agree is probably true.
Secondly, we wanted to petition her for bankrupcy because we knew she owed others money, and this was not to get our money back as we knew it fruitless, but just to make life so difficult for her as she has now for us (tit for tat)
Thirdly, thank god, we have since found that she has done an IVA. It seems as though all the companies involved have to agree and this company that she has the loan with are the last to decide whether they accept the agreement. It is a possibility still, that they may not, and my partner still has to continue payments. We shall see. But bankruptcy is not an option for us. We don't owe enough money to be bankrupt.
Nonetheless, lessons have been learned , she's lost out on a 20 year friendship which you can't buy back with money even if it were a million quid.
Thanks again guys.