OCD - what’s helped?

Can anyone who has OCD share with me what’s helped them most? My son was having nhs therapy which hasn’t really helped him - and now they’re saying they’re going to discharge him (which is in itself weird because how can they discharge someone if they haven’t helped them get better?!). 

can anyone recommend anything? Maybe a really good book or something? Because I think we are not left with any option other than to try and help ourselves with this. 
Any advice will be gratefully received :)