my credit scoring dropped because of cellc ********* actions

Good day im going to start with saying that my main concern is that for the past 3 to 4 years ive been trying to apply for a home loan i did everything in my capabilities to qualify and as a result my scoring was increased from 537 to 643 which is proven that from 620 above is an ideal scoring to be approved for a HL in that pillar or requirement ,however i then app**** through SA homeloans which they pre qualified me and i was house hunting and found something suitable for me and my family in which i had to just fill in my OTP letter with a house amounting R500.000 however last month as confirmed on recorded calls cellc can debit my acoount on the 20th of every month there was a technical error on their side so which they chose to debit my account on the 25th without any confirmation of their issues experienced which upsets me because the 20th was on a saturday in the month of march but they debited the Thursday the 25th of march and not the next working day as a normal institution which was the 22nd of march 2021 the Monday which was apparently a bounced debit order in which my scoring was affected ,as mentioned my confirmed debit date was on the 20th they then debited R109.00 on the 19th of April which led my account into a minus which is too a bad reflection with transunion because it shows no saving at hand if ones accounts goes into a negative ,when i called in they said its too early for them to know for what was R109.00 debited it shows pending ,on the 20th April they then debited previous months debit order plus this months debit order of R622 and some odd cents and still too they can not determine what was it debited for the R109.00 my issue is not the money its the fact that i told them SA homeloans gave me a deadline to submit my offer to purchase letter within 2months and i cant now because of their actions which resulted my credit score dropping drastically .i pleaded with cellc to instruct transunion of their faults and technical errors that their had and to get my credit score back up and running before my deadline to submit my OTP letter ,i am still awaiting a call from management of cellc to get back to me which i know for sure they wont call me back nor will they rectify their actions .Can i please know whats the way forward !!