Cash crusaders day light ******* and useless dixion brand

I purchased cash crusaders tablet..their dixion brand around October 2019..December 2019 it started its battery ended quickly and died if its not inserted in tge charger.. I took it back to the store at Hatfield plaza January 2020 as it has a 12 months gaurentee..i went to the store 1st week of January and one of the consultant Samukelisiwe told me their repair department was not opened and will call me when they open..she never did call so i went back to the store February by this time the phone at the back is swollen, she took in the phone and booked it for repair, i went back March 21st before the lockdown only to have her telling me she had tried to call me, the phone needs R100 to be paid as the battery is the problem but not part of the guarantee after she claims that its my fault as i must have over charged tge phone..which is obserd to me as to how can one over charge a phone? Iv had many phones charged them a few minutes even after being full but none of their batteries died of burst. Anyway i agree to pay the R100 for the battery and expected to be called in after lockdown to collect it but to my suprise i was called in saying i need to pay another R300 to thei repair department as the battery cannot be changed by tgem at cash crusaders. I bought that tablet for R750 npw i must pay half of its amount to get it fixed whilest at i never even used it for even 6 months? Kindly assist me in this matter as i want a new phone or they refund me my money back