Welcome in the difficult reality of finding an internship in England. Those companies and schools exist because they know people are ready to pay to be provided an internship because it is extremly difficult to be offered an interview by any company expecially when you are not British yourself. I admit I have also asked one of those companies (Internship In London) to help me with finding my internship. Finally they found me the perfect one for my future career. In the end I do not regret having payed that fee as the internship was great even though I would have prefered to find something for free too. You have 2 options: to pay, gain time and energy and have rapidely an internship for sure or to spend time and energy but not pay. I thinkk both are equivalent.