its best to have a paper trail give the employee a written warning with all of the pertinent facts if it continues than fire the employee
you will first have to go though disciplinary Procedures. first those in the contract you gave your employee and make shore they comply with the latest rules if you do not go through the correct procedures you will be open to being done for wrongful dismissal. employee have more right now than ever. be very careful
If in the UK and you have already given two warnings about being sacked ,then you would have to give a written warning then if the complaint is still there it would be instant dismissal.
Not before you give them a verbal then a written warning. Then be ready for a lengthy tribunal for unfair dismissal.
Obviously yes.
you have grounds for a final written warning