"Securitas security service" can this company put hands on you for any reason?

I am an experienced security operative. The company doesn't matter as long as those staff are holding appropriate sia licenses. Of course I am assuming you are asking about securitas in the uk. If elsewhere my answer may be less helpful.

They can use physical force to restrain you if they can justify a belief that that you pose an immediate threat to the safety of themselves or any other person or property.

They can use physical force to remove you from, or prevent you from entering any premises for which they are responsible.

They can also use force to effect a lawful arrest should they have sufficient grounds to believe you have commited an offence that allows a citizens arrest to be made.

In any case the force used must be reasonable, proprotionate and neccarsary.