HELP Ive received a "Default" Notice that I dont agree with?

I recieved a "Default Notice" letter today from the credit company that manages my car insurance payments. I know I have missed 1/2 payments on a previous agreement I had with them but I always payed with two days of noticing it hadn t gone through.

Anyway, I started a new agreement with them this month and I forgot that the payment date had changed becuase I didnt renew the policy straight away, so I forgot to transfer the funds to my account for them to take. I made payment within 5days of realising this was the case. Today I recevied a letter of default notice which states they tried to collect the money on the 8th july when in fact they didnt try until the 22nd. And I read that thye issue notices after 3-6missed payments, now does this include previous agreements? as I signed a whole new agreement.

please help it was a stupid mistake and I dont want a default on my credit file.