Candy CIC60 condenser dryer?

For six months, it's been getting worse (and it's only 15 months old). It works about 40 mins, then stops altogether. Occasionally the "clean filter" light will come on. Except the filter is as clean as a whistle. The temperature keeps going mad, going onto high heat and shrinking nearly everything that goes in it, and occasionally burning them. Unfortunately it's too late to get it fixed under guarantee, but it's been the same problem the company have attended to 2x under guarantee. Any ideas, is it simple and cheap to fix?