Coolant leak

There was a recall on my car and I brought it to the dealership and had it serviced in November 2018. The recall was due to engine overheating and catching fire I believe. So that was supposedly fixed, while it was in the shop they said some kind of sensor needed to be replaced and that wasn't covered by the recall. So I paid for that and got the car back. Everything was okay with it up until this past week. There is a light coming on saying " Engine Coolant Over-temperature" and the car will not go anywhere when put into gear. It will just shake and does not drive at all. So I had it towed to the same dealership that I had it serviced at in Nonmember. They are now telling me that the "heater hose" which is connected to a part called a "T" (no clue what this part actually is) is leaking coolant due to the "T" being broken and needing to be repaired.
My question is that I'm needing to know if this could be related to or caused by the same dealership "fixing" my car last time it was there. The warning lights that are on are the same now as when I brought the car in for the recall so I figured it would still be covered under that recall notice, but it's not. Sorry for the long post, but any insight would be greatly appreciated!