Double billing

My membership was activated on the 1st of April 2015 (I was only informed on the 10th April 2015) and at the same time I was billed for BOTH APRIL AND MAY WITH NO PRIOR WARNING!! I had only expected to be billed for April and thus was left IN THE MINUS with my bank account with NO MONEY FOR THE REST OF THE MONTH. Nothing for food, fuel, other expenses or emergencies. I immediately called Customer Care and queried the situation (Call ***). They told me that there was a mistake and to expect a reimbur*****t by Monday. This still left me with Sunday of being broke. On the Monday morning I called again and was told that it would be sorted out within 48hours. I contested this as it had already been 48 hours. I was then told to expect a call within the day and that it would be sorted out. At 3.20pm I called again, after having heard nothing. I was only THEN told that the billing was for April and May. When I asked why no one had warned me of this I was told a very polite \Sorry