Salary Overpayment- Now Retrenched. Worth Fighting?

Location: Malaysia

TLDR: I was paid a 50% salary increase for 8 months, was told by HR to hold onto the money, later forced to repay ~5 months’ salary without being given an official revised compensation statement. Now retrenched and wondering if it’s worth pursuing the company to recover the money.

Hi all, I recently lost my job due to redundancy and would appreciate some advice on whether it’s worth pursuing my former employer over a salary issue. I worked for an MNC for 7 years. In my second year, I unexpectedly received a 50% pay increment during the annual performance and compensation review. My manager later told me this was a mistake and that my actual increment should have been 5%, and that I should ignore the base pay stated in the review statement. Despite that, the following month my salary was paid with the full 50% increment. I immediately informed my manager, who raised it with HR. HR told me to hold on to the money until they formally requested it back. I later found out that several other colleagues were affected as well, and this situation went on for about 8 months. My manager repeatedly questioned HR and upper management because she was unhappy with the situation. One affected colleague even had a screenshot of an email thread between HR and our manager stating that the 50% increment was justified due to a “market adjustment.” Apparently, the increment was higher than what my manager herself was receiving. After 8 months, HR finally provided a breakdown of the “incorrect” vs “correct” salary and asked me to repay the difference. I requested an official revised compensation review statement, but HR said they were not obligated to provide one. Eventually, I repaid the amount, which was roughly equivalent to five months’ salary. The explanation given was that it was a mistake made by a former head of HR who had already left the company.

My question: Is it worth pursuing the company, given that they never officially issued an adjusted compensation review statement, and should I request that the repaid amount be returned?