ReAssure review: Private pension scheme

I have for several months been attempting to receive my pension lump sum from this company which is based in the UK. They stated that payment was sent on the 3rd of March but nothing has appeared in my account. They are difficult to contact. I have waited at least 40 minutes on the phone, emails are only responded to after a week, one is discouraged from writing e-mails as they state that doing do would delay matters further. The FCA and Pension Ombudsman, regulatory bodies in the UK have been next to useless. I have formally complained to ReAssure who told me that they would assign a dedicated person to my case, but no further information was given. Another complaint's forum Trustpilot has a great many complaints about this company. This company is doing all it can to delay the payment of its customer's money, and no one seems to want to help.