Significant investment loss over a short period after withdrawal

I cannot let go of what happened with my claim after my resignation February 2020. From the payout that I was supposed to receive, over R130 000 in less than a month was lost from my funds which I invested over 15 years. I queried this and they gave me a hard time in giving me reasons and evidence for this loss. They blamed it on the pandemic recession, but my withdrawal was submitted and recieved by Alexander forbes before than. Even so, there's no way that I could have lost over 30% in a short space of time, that means should I have not withdrawn my funds when I did, I would have lost 15 years of investment within 3 months. I do suspect that something wrong happened somewhere and it was a great opportunity to blame the pandemic.