Early RAC car insurance cancelation fee can they charge whooping 115 pound two months due to end of my contrac?

So I av canceled my insurance today with RAC although I had money taken from my account yesterday for the following month it was 115.29 pound so when I rang em this morning to cancel and get my 115 pound back as I did not gone over to the next month June now they saying that they won't give my my monies back due to earlier canceletion fee I understand that there is fee that apply for this canceletion but is it fair to charge me whooping 115 pound for it when my insurance was due to finish this julay? I understand up to 50 pound is reasonable fee charg but 115? Thats bit too much! Now they say it is legal and they won't give it back to me not even partially can they do that? Wot can I do to get at least half of it if I can't get the wholl lot? Thenks for replay