Paid Voluntary NI contributions - How long is updating of the online NI records taking?

I'm in a similar situation, I paid 4 years voluntary NI back on the 15th May 2024 by bank transfer and these are still not allocated to my NI account. I did however have a notice appear on my NI records saying "There is a short delay in processing some payments. Your forecast will be updated as soon as possible" this notice then disappeared at the beginning of August and still no NI contributions allocated!!

Hi G Brett,
May I ask that you call our National Insurance Helpline on 0300 200 3500 (from the UK) or +44 191 203 7010 (from overseas) and they will be able to check your National Insurance account and make sure that we have received your payment.
Please have your payment details handy when you call them.
Thank you. 
 

I paid NI Contributions for multiple years on September 3rd 2024. I called the helpline and got confirmation over the phone that the payment was received and that my account would be updated. However, no update has appeared yet. Do i need to call again?

Hi Tony,
We are currently dealing with a high volume of voluntary payments.
The timescales depend on the circumstances of your payment and the National Insurance class.
If you paid for an abroad period it can take up to 29 weeks to allocate the payment to your record, if it is a domestic Class 2 payment it can take up to 29 weeks and a domestic Class 3 payment can take up to 8 weeks (based on the automated system allocating the amounts).
The domestic Class 3 payments can also be allocated over the phone, if you’d like to call us on 0300 200 3500 to do so.
However, abroad payments and Class 2 payments take 29 weeks, due to the high volume of other payments in the queue needing to be allocated.
Thank you.

OK. Thank you for the clarification.

I have paid extra contributions from Australia, I have called the help line and was told they would expedite it. I have received my original pension amount, not the top up. Does anyone actually know how long the process takes. HMRC cashed the cheque two months ago?

Hi,
You can find out when you can expect to receive a reply form HMRC here:  
Check when you can expect a reply from HMRC
Thank you.