Hi,
Are you sure its jean dye on the carpet? Is it proper blue or just a grey patch like soiling?
I would get a written liability waiver and go hell for leather on dye transfer techniques. Red RX cold, rinse. Red RX hot Towel, H2O2, H2O2 ammonia, Bisulphite cold, then hot....
If it doesn't work inquire about the carpet knife solution and sub the work to a fitter who can patch it adding 25%.
Charge for each step and lay out the costs of each process, keep them informed and don't be afraid to charge for things that dont work. Just be honest, people like those who fail trying hard sometimes and if dealt with right will pay.
If it is dye transfer, you prolly wont get it out, but its worth a bash and can earn.
Graeme
Access Cleaning Solutions