I’m not a lawyer but all of those accusations are very, very serious. Was there any documentation taken at the “Grievance Meeting” detailing specific incidents or customer complaints to justify those accusations. Was a HR rep present at that meeting? Did you sign anything? The laws are one thing but the protocol in which these corrective actions or performance reviews are handled needs to remain professional. None of what you mentioned is a good sign to indicate your employment with that company is guaranteed. Don’t get caught standing on your heels. Start looking for another job ASAP.