Complete online self assessment problem

As I now earn above the £50000 threshold for child benefit payments I now need to complete a tax return. I have been online four times now to complete the Registering for Self Assessment and getting a tax return form. I have never heard anything back from HMRC. I thought I should have received a UTR number within 15 days. I have never received one. I have phoned HMRC to be told I needed to complete this online and explained I have done this four times. The lady I spoke to was unsure how to help me. Not sure what I am doing wrong? I just want to sign up for self assessment and complete a form but have had no luck and never hear anything back from HMRC.

Hi

I'm sorry to hear that you've had issues receiving your UTR.
If applied for correctly, you should receive your UTR around 3 weeks after applying.
If this amount of time has passed and you still haven't received your UTR, please contact us by webchat or phone via Self Assessment: general enquiries , and we can register you for Self Assessment.

Thank you