I've made 2 loansby them over the last 2 months and now i dont have the same number anymore the old one registered on my name in there site is inactive and not registered on a network anymore

I've made 2 loansby them over the last 2 months and now i dont have the same number anymore the old one registered on my name in there site is inactive and not registered on a network anymore. I've been trying all the possible ways getting hold of them but nothing they tell me to do is helping me to change my cellphone number.. but they can send you very quickly message money is due and you payment is due and take the money like in a blink of an eye but no help to change you details