Vitality watch

I need vitality to please give me an explanation regarding my fitness watch. I am getting calls from Teljoy saying my account is in arrears, yet the agreement is 100 percent payment if my goals is reached monthly. I have this watch for months and now suddenly I get this, I cannot remember singing a agreement that said I would pay anything, now they say they only pay 300 and I have to pay the rest, does not make sense