THE GLASS ON MY 300 IS SPREADING!

Hi all, much to my disappointment the glass on my custom 300g is spreading at the base! its 7ft long 34 in wide and 2ft high. I had the top brace put as high as possible and it has a double base, the glass is joined by black sealant and was made by a top aquarium builder in the uk... after having it 6 months i noticed a few air bubbles along the bottom edge where it joins to the internal second sheet of 10mm glass, now they have expanded gradually (had the tank two or three years now) to the point where i have bought some 1'' black ratchet straps and this morning im gonna strap the bottom up to prevent it from going any further....

why has it done this, due to me having the top brace 10mm down from the top lip or just bad workmanship?
gonna email the company this morning and see what they have to say about it, should have contacted them when i first saw the air bubbles i know but still, could be dangerous if the front pane broke free!!!

i just messaged the guy and im waiting for a reply, they built it and im hoping that they are honourable enough to fix bad workmanship!? its got to the point where i need to do something, now i need to make temp accommodation for the fish!!!

hopefully... ive emailed and tx now. the front panel is 1.5mm proud of the base panel in the centre. ive now used a builders 1 inch strap and cranked it as tight as i can, pretty sure the corners can shift now so the panel cant just pop off!!!

i was thinking wheelie bins x 2 lol... less space, i still have no reply from the company, i wont name them yet... ive ratchet strapped the top and bottom atm, its safe now until it gets sorted... gutting, you prob already know the company evz's, i read on their site and they give a 3 year warrenty which im inside but with a shady small print!