What's with everybody? She didn't post in DIY nor is she asking for a shop recommendation. There's nothing unreasonable about taking a malfunctioning piece of dive equipment to a shop to get it serviced.
To answer the question posed in the thread title. "Is this possible 3 dives after having equipment serviced????"
Yes, it's possible and unfortunately not uncommon for a repair to be done incorrectly. For example, they may have just cleaned and lubricated the inflator rather than fully servicing it or, more likely with this part, replacing it. That could have been enough to get it working at the moment, but not enough to fix the underlying problem.
Does the invoice show that they replaced the part? One suggestion for the future is to ask for replaced parts to be returned to you.
To answer the question posed in the thread title. "Is this possible 3 dives after having equipment serviced????"
Yes, it's possible and unfortunately not uncommon for a repair to be done incorrectly. For example, they may have just cleaned and lubricated the inflator rather than fully servicing it or, more likely with this part, replacing it. That could have been enough to get it working at the moment, but not enough to fix the underlying problem.
Does the invoice show that they replaced the part? One suggestion for the future is to ask for replaced parts to be returned to you.