I want to speak to UK person in retentions

There isn't a direct line to UK call centre staff.  All calls go through the same IVR system which directs the call to the first available agent.

You may have a better chance of speaking to a member from the UK teams if you try calling around 8am when lines first open.

You should select options 1, 1, 4 and 4 when dialing 150 from a VM landline, or 0345 454 1111 from any other phone, which should put you through to retentions (thinking of leaving)