WARRANTY INVALIDATED UNFAIRLY!!

EDI ADAPTOR the power-supply to my existing adaptor burnt-out this due to fact I had to "rig" the power-supply into an existing molex power connection. Reason is I do not have spare sockets left. On 6 Dec 2023 I approach Matrix to enquire if possible to purchase the power-supply on it's own. I was informed that I have to purchase the whole unit AGAIN!. Before purchasing I informed them that I have to "rig" the power-supply meaning cut it to affix via "ceasarean" connection to an existing molex. I promptly purchase via online order 10 Dec 2023 item which came without any manual nor warrenty leaflet whatsoever. The adaptor is a unit on it's own and power supply is not permanently fix but is also a unit on it's own. Package consist of 3 components. Collected item 6/7 Jan 2024 at southgate branch. I affix the new power-chord by extension to an existing molex power cable. Everything worked as planned! Because I now have two EDI adaptors, on 21 Jan 2024 I decided to "swop" with "new" unit as it looks different to the existing one.(existing is red in color and new is black in color". To my horror my PC froze and give me warning about hardware failure. I re-check if device was properly fitted, only than did I realize the new unit power light was off - that means it was "dead" unit. When I called to advise matrix they inform me to return all the parts, which I did. However the supplier of the unit return it without testing that my warranty is invalidated because I modified the device. How ingenious that adapting a power-connector attached to molex can be viewed as modification/damage. Any IT person can attest that the work-around to extending molex-power connector is by "bridging" which means cutting - it is not damage nor modification. I proof to them that existing unit is functioning but this unit is not functioning using the same connection extension I rigged. Clearly use warranty clause that does not exist since the device is supp**** "voetstoets" with no instruction manual or any other information supp**** in writing or otherwise. The item was ordered online and paid for