how can i fix my hotpoint aquarius vtdoo tumble dryer?

my hotpoint aquarius vtdoo tumble dryer sometimes makes a grinding noise. it is still under warranty, i have been informed that the frame is twisted due tom the fact that it is stacked on top of my washing machine and i do not have a stacking kit. any one i speak to tells me this is a load of rubbish and sounds like warranty people are trying it on. all help is appreciated thanks