Drafty Bi-Fold Door Advice Please

reverie

Hello! Please may I pick your brains?

At the back of our house, we have a kitchen extension with a wide stretch of wooden bi-fold doors across. 5 doors in total, so they stretch probably 4 meters. They were fitted about 8 or 9 years ago (when bi-fold doors were just trendy I guess?) by the previous owners.

They look beautiful but there are gaps at the top and bottom between each door where the seal under the door stops to make way for the hinge. So between each door there is about a 5cm gap. At this time of year this causes quite a draft.

Also, I'm worried about their security. The door hinges seem to be secured by an 'up and down' handle that puts a pin up and down internally when moved (like in a uPVC door but without the actual lock, I think) does that make sense?

Anyway, I have had one person out to look and he said that retro fitting repairs to these types of doors without knowing who made them is a nightmare, they are not made like that anymore as the mechanisms are sealed and hidden. So basically, we're stuffed and stuck with unsecure drafty doors or a new set of doors?

Any suggestions or thoughts gratefully received! Thank you.