Glass Shower Door Doesn't Stay Closed

My glass shower door keeps popping open & I think the rubber gasket(?) has worn out & is not providing the proper seal. Who can I call to replace that piece, a shower door company or a handyman? I'm not the least bit handy so trying to replace it myself is out of the question.

Mrs. GB

Kanter Plumbing Supply in Orange (Just past the White Castle on other side of Scotland Rd. has doors you could buy and replace the old one.) 

On our shower doors (on a hinge, and from probably the 1980's), that 'rubber gasket' was actually a magnet that is in a channel near the edge of the door. This magnet kept the door shut.  

One of our shower doors stopped staying closed, and I found I could slide the strip of rubber magnet up and out of the door (the channel was open at the top of the shower door). Then I rotated the magnet so the other side (which was cleaner) was now facing outwards, and slid it back into the door's channel. Then the door was able to stick closed again by that magnet.

There are also ways to shift the door and the magnet trim on the frame for better contact:

Thanks for sharing the helpful video. You can call the professional to get it fixed properly.