If an independent contractor who was hired to sand and re stain floors completes the job, but the client then starts seeing black spots (from extrmeley fine particles that were not fully picked up when filing the scrapers to sand the hard to reach areas) - a mix of latex stain was used (water based that caused these shavings to turn black) and offers to fix the problem by re -doing the sanding and staing complimentary but the homeowner says no they want a full refund - is there a grounds for the contractor to have to full reimburse the homeowner? PS - a balance of $4200 is still owed to the contractor for the final payment.