Lifecell International — Harassment - Sending continuous reminder emails and messages after payment

We had a baby boy in 2021, April. We stored our baby stem cells in Lifecell. We paid some amount and other amount of 30, 000, we need to pay when our baby boy turned one (2022, April). We had given them a check of 30, 000 in advance. However, I called the customer care and asked them if I can pay the amount in advance. They said, Yes!. I paid the amount in Feb.
(attached, the copy for the same). Now, they have been sending email reminders to me and messages asking me to pay the amount. I called customer care many times and they said they will fix it but they never did, One person mentioned, you can ignore them as I can see you have already paid. But, I cannot just ignore many emails. Once, its fine but how many reminders I got is unbelievable ( Attaching the same screenshots). What if they consider I did not pay and take some stupid action against me or the stem cells, I wasted so much time in talking to them but no resolution. They became a big pain. I lost my trust in them now and in their systems. Very outdated I believe.

Regards,
Vinay