Hi Shabs
Thanks so much for taking the time to get in touch.
In this instance I would absolutely recommend going to the app and changing the password on your account. You can also set up two factor authentication on your app, meaning that if anyone attempted to change the password or hack your account, you would be notified and given instructions on how to fix this.
With regards to discussing the payments made onto your account, the best bet would be to contact our Customer Services team - whilst I appreciate you've already tried this, our Customer Service team really are the experts in being able to understand what has happened and will be able to rectify this. The best contact number to call on would be 0330 333 7442 8am to 8pm Monday to Friday and 8am to 5pm Saturday. Mondays are usually our busiest days, but I'd still absolutely recommend giving us a call.
I really hope this helps
Thanks again
Pete