6 digit verification code continually rejected

I am trying to log in to my account to top it up. I have entered my security code and phone number and then asked for 6 digit verification code. It comes through and I enter it but it is rejected. Each new code is rejected and I am typing the correct number. How can I get into my account to top up?

Uninstall the app, then install it ones again. Probably it has to be synchronized (challenge- response scheme)