WhatsApp Business API Troubleshooting

I already have a verified business account and verified phone number for WhatsApp Business API and had a verified payment method (something gone off here, possibly - not sure). One app was created and it actually worked fine - sending authentication messages to real whatsapp phone numbers.

Trying to now create a new app under the same business entity and the setup seems to be (at least to me) exactly the same as the previous (and still existing app). However cannot send any messages to whatsapp.

I want some one to come in, identify the issues or issues, document all of it, fix the issues or issues and document the fixes as well.

If any one is willing, let me know time and cost estimate.

Update: App is created, everything actually seems to be fine but the messages to whatsapp are not being sent. I dont believe this a big problem and those who set this up earlier will probably be able to find the issue in no time at all.

Do let me know interest and we can discuss this further, the price posted is not cast in stone, but I do need this to be reasonable given the actual problem.