Lewis debit earlier that agreed date

When I opened an account at Lewis in 2025 November, the agreement was that money would be debited on the last day of the month, December they sent an sms to say they will deduct earlier and I agreed and I even gave them an earlier date to debit. From January they were debiting on the last day of the month. Until yesterday, my sister sent me money to take my son to see a specialist, they debited that money, no consent from me, no communication that the money would be debited earlier this month, I mean last day of the month does not fall on a weekend nor a holiday. I am stuck with a sick child. When I call them they said I gave them consent, I just went through my contract and there's nothing about that except the earlier deduction with be in December. I am very disappointed and hurt because now they lie and said whenni signed the contract I agreed when there's no such in the contract. I will never buy anything from them after this. What's the use of getting into agreement if the other party doesn't hold their end of agreement