HMRC’s announcement includes the news that from 8 April:
The PAYE helpline will no longer take calls from customers chasing the status of repayments, directing them instead to check online.
The VAT helplines will only be available for 5 days per month, immediately prior to the monthly filing deadline. At all other times customers will be directed to online services.
Between April and September, the Self-Assessment (SA) helpline will be closed. Furthermore, although it will operate between October and March, it will only take ‘priority calls’; and all queries that HMRC believe can be dealt with online will be directed to the online services.
https://www.pcs.org.uk/news-events/news/hmrc-calls-taking-too-long-stop-taking-calls
Not sure how this affects the pension phone lines