Martin, I know only one mostly effective way of handling Oodinium, and that is a treatment with fresh (yellow!) 2-amino-5-nitrothiazol; if the powder has become brown already, you can forget it and throw it away. The substance was formerly in Spirohexol (JBL) and Hexa-Ex (Tetra), but both companies seem to have changed the composition of their products; the new ones do not seem effective any more. The pure substance is hard to get hold of since (at least in Germany) only veterinarians are allowed to buy and use it. So we are largely left with conservative treatments. Methylenblau und Malachitgrün are not very effective.
I think, the best conservative treatment is that you have used (rise of temperature)and its optimization suggested by Rafael. But you could try to make it still more effective by adding normal table-salt (=Natriumchlorid), about a table-spoon for 10 liters. Paros do not like Calcium in their waters, but they stand quite a lot of Natriumchlorid. The parasites seem to leave the fish-body in the course of several hours or days. Then you should place the fishes in fresh water with the right water values. The method is not sure, but generally safe.