Spares shop not to be trusted

I purchased a new engine from them on behalf of employer for R60000.00 and as it is a chinese motor they did not give us any type of guarantee upon purchase, this particular motor did not run for more than 2 months, we then had to get a diesel mechanic to come look at it as there was very disturbing noises coming from the motor, he found that the pushrods were worn out and bent, we then proceeded to contact black & white truck spares pretoria and were told that they do not accept responsibility for it, so we bought new pushrods from them, after doing the repairs the motor was running like it should. 2 weeks after these repairs were done we had to call the diesel mechanic out again he found that the push rods were once again bent and worn out, i then proceeded to contact black & white truck spares again and once again they did not take any responsibility for the very bad quality spares they sell, they did not even offer to give us pushrods free of charge, they were absolutely no help at all.