You can do it yourself - it's a bit of a bore but it is much cheaper.
I used
www.mothkiller.co.uk. for all the sprays and foggers. The sad fact is that you will have to treat the house more than once. I did ours last year and the little blighters have made an appearance once again.
Better to treat either by using a company or doing it yourself rather than finding maggots in carpets in parts of rooms that the hoover doesn't reach...ugh!