Accidental refunded twice by investment platform

Hi All:

During april 2018 i opened a LISA (AJBell). After opening the account i realized i went over my allowance for the year (i add my ISA with a diff provider). I instructed the AJBell to cancel my account immediately, as this was inside the cancellation period there was no issue with the cancellation however it took them almost 1 month to get my money back, as you might imagine at that point i was quite upset as it seems AJBell did not have a process in place to deal with LISAs.

After giving me back my money, i got another identical payment after 6 days. I have notified them of that situation via email but they are yet to contact me. I am keen on contacting via email to ensure i have records of the conversation.

Can you provide me with some feedback on what should i do next? It has been 3 days since i was told they will contact me. I am assuming that if this is an issue on their system they will realize and contact me. I have taken steps to notify them, so is it fair to say that i have done my bit? Or do i have to chase them actively to get them back the money?