I really need advice urgently on what to do and what my rights are with this issue. I put a deposit down on my first bike last friday and the bike was to be supplied with a RWC. It needed chain and rear disc. The sellers mechanics did everything required for the RWC but also changed the throttle cable which was a little loose but not damaged without telling the seller about it and they now want to charge ~$150 for it ($40 cable $110 labour as it was a tough job aparantly). They also claim that the actual mechanic who stuffed up quit this week. They replaced the cable without telling her but refuse to take blame for it and won't supply the RWC unless someone pays for it. She refuses to pay for it and now wants me to pay for it because she only agreed to pay for the parts the bike needed for the RWC. She started asking if I wanted to back out (I think someone may have offered her a higher price?). Even if I do pay the $150 for the cable the bike will still be a good deal and I don't want to lose the buy but these actions buy the mechanic are unethical and dodgy... Can I agree to pay her for it and then chase up the mechanic... i know who it is? What should/can I do?