New Gateway ID computer loop problem

I've totally lost my old ID - and gone through the process to get a new one only to be taken to a page saying We have found your account now login using this number - but only giving me the last 4 digits. what is the point of being given a new ID number only to be told to use the old one. It's the weekend so I am trying to sort this but no online support. Has anyone else had this problem and how did you sort it out Please!

Hi Marymary,
As part of a rolling programme of security improvements, HMRC is limiting access to Personal Tax Accounts (PTA) to one set of sign in details for the Government Gateway (GG), (this is a GG user ID and password). 
Until now, it has been possible for a customer to have more than one sign in for the GG to access their PTA. This often happens if, for example, they have forgotten or lost their user ID or password and set up a new credential rather than recovering the existing one. 
Having just one sign in makes it easier for customers to remember and recover forgotten details.  This change also makes it easier for us to protect customer accounts.

Please call Online Services helpdesk 0300 200 3600 where we will be able to assist you
Thank you.