Jura Pressure Hose Bursts

I have an Impressa S9 One Touch that is about 15 yrs old. While making cappuccino, one of the mesh pressure hoses blew out with a bang. This is the hose leading from the steamer to the valve that has the four supply hoses coming out of it. Apparently this device is operated by a solenoid that opens the valve to one of the four hoses to allow steam through. We've always performed the decalcification maintenance when prompted. I have two questions:

1) What would cause the hose to burst under pressure?

2) Where can I purchase a length of this hose where I'm not price gouged? $28 for 1 foot of it is ridiculous. The dimensions are 4.2 id x 8 od mm. I've found that 4x9 mm or 5x9 mm are readily available and much cheaper. Has anyone used either of these in lieu of the OEM tube?

Thanks in advance.