Stage warning issued with no return to work??

[Cyclopz]

Greetings one and all, it's been a while since I posted here but I am still in the business.

I am asking this on behalf of a work colleague and to be honest this would probably help me and others.

My colleague has been issued a stage 1 warning for being off sick and no return to work was issued, a simple stage warning was issued and that's all.

Does anyone know the procedure and if there are time limits with regards issuing a stage warning after returning to work from being absent?

Is there any way the stage warning can be nullified due to not following the correct procedure or are those days long gone?

I mean can the company pretty much do what it likes now or are rules and regulations still enforced?

Many thanks.