The error 'Something went wrong with your request, please try later' is often caused by an issue with the PAC you're entering. This could be any of the following:
Wrong PAC/MSISDN (mobile number) combination - a PAC is issued for a specific MSISDN
Error while entering the PAC/MSISDN
Error in PAC given by old network
PAC already used
If you're certain you've entered the details correctly, please try using a different browser or device. If the issue persists contact your old provider and ask them to re-confirm the PAC. When they reply that it's correct, ask again!