Game store credit card

Hello peter On the 23 November 2019 i got a game store card with a credit limit of R7000 i biught a fridge for 5100 and in january i bought some groceries and i had 900rands left to spend , on the 1st of feb 400r was debitted from my bank acc . When i checked on the Game store app i had 98 rand to spent then i contacted call centre they told me my credit limit was reduced to 5500rands , When i asked why, i told that they cant tell me. Now everytime when i get debited from my bank acc 340 the amount that i owe them is not changing and im not getting answers from them why. Last month i owed them 5256rands, 340rands was debited from bank acc. When i checked yesterday its showing that i now owe 5178rands . This is stressing me . Their call centre are useless . Somebody please help