We have problems with ABSA the past 20 years

ABSA Home loan account No. *** On 27/12/2019 we ( me and my spouse) withdraw money from our flexi credit R3000.00 at Bloubergstrand ABSA in Cape Town whilst on holiday. On the 16/01/2020 I received an email from ABSA that my monthly installment increased from R3196.98 to R4029.61 because of this withdrawal - WHY? - Its credit we have in our account. I've mailed them and request as to why my monthly installment increased with over a R850.00. The same day 16/01/2020 I went to ABSA in Rustenburg Waterfall Mall. The Lady that served me also could not understand the reason for the increase. She phoned ABSA HOME. They couldn't give an answer. She printed me a statement and letter of the mail she send to ABSA HOME