ALL Tune and Lube ATL Let go for being to slow woodbridge, Virginia

well recently i saw a new automotive shop opening up in woodbridge,va so i stopped by and filled out an application and had a interview and got a call the next day asking if i could start on monday so i did the first week i was putting stuff together then the other new employees showed up anbd so on. so cars started coming in and service was getting done and so one. well about 3weeks after i got hired i was called in to the office and was told by the owner,manager that they have been doing alot of thinking and that they going to let me go and i asked why they said becasue business was slow and my skill level wasnt the best, then they said sorry and thety if they get busy they will call me to come and work for them again but yet they hired another person, and the part that im not happy about is during my interview i let the rm and owner know that i have a disablitiy, and that im slower then everyone else but i can still do that work. they said thats fine and still hired me, but 3weeks later they let me go knowing that i wanted to start a career with the company  and when i do stop by there to see if they want to bring me back or talk to the techs the owner always tells me to leave. but its ok if i stop by for a few. im just very mad how i left my fromer job to go to atl and they cut me lose after 3weeks. and i got along with all the people there. is there something else i can do? im tired of getting let go and i have two kids im trying to take care of and now im working a part time job barley making it by, i was counting on atl to start my career and start leanring company policies but yet got let go.. what do i do now?