Been paying extra payments for pension but did not get any tax deductions

Im not sure im explaining it correctly. But since 2018 ive been paying the voluntarily payments to add more into the superannuation/pension/401k company system.

From my understanding im supposed to get tax rebates but I dont believe I ever did. How could I validate the tax rebates?

Can i speak to someone professional in Japan that can look into these things?

I was paying 28,000yen extra per month and just stopped this year April as I changed jobs.

Trying my luck here incase someone was in a similar boat 🙏