I wouldn't say the banana temps were because of too cold temps. Low 60s is no way too cold for the S-04. Rather, my assumption is that you started the fermentation off too warm, probably even pitched too warm as well (just a guess, but its a normal new brewer mistake). Then, my assumption is the stall happened (if it indeed happened, you may just be done) when the exothermic activity of the yeast slowed down and the thermal mass of the beer began to merge with the temp of the ambient room.
Just a guess. I could be wrong but I have never experienced banana esters at cooler temps with any english strains. One thing you should do is get a sanitized racking cane and rouse the yeast. English strains have a tendency to flocculate and leave a higher finishing gravity. Also move the fermenter to a warmer part of the house. You want the temp of the beer to be around 66-68 to get the beer to finish. Do you have any idea what the gravity of the beer is right now?