How can I fix Hotpoint Aquarius Condenser Tumble Dryer TDC30p ?

A patch on the drum of my dryer has corroded exposing a rust like colour, will this stain laundry, can this be treated? I have not used the dryer for quite some time as it is working but remains cold will not heat up could this be just the heating element or could it be something else as well? Would like to have the dryer repaired but do not want to waste the money if these problems cannot be rectified