Website errors keeping me up at night

Today I repaid my loan and their site isnt showing it. Their site keeps giving me an error message that they cant retrieve my loan details, to try again later. What worries me it still shows that Im owing them and I can pay them back the same amount. I know they will attempt to debit the amount from my account and I dont know what they will do when they dont find that money even.though I have already paid it back.