You can try this company https://www.bsi-renew.co.za/get-a-quote/ they have an option to rejuvenate a battery.
I have sent my 100ah gel battery today.
My issue was i could only get 0.26kWh from this battery (its a 1.2 kWh battery, I should be getting atleast 0.6kWh using the recommended 50% DOD)