The internet Archive has several Windows 7 OEM iso's with direct downloads or torrent links.
You didn't say what brand. OEM manufacturers have embedded SLIC (software licensing description table) with the key already in the bios. Apparently any Windows 7 OEM iso will work.
The Internet Archive has Windows 7 OEM ISO's available for direct download. Go to Archive.org, Click on the Software icon (looks like floppy disk icon to me), in the window that comes up on the left side is a search text box. Type "windows 7 OEM" press enter, it will show the results, an OEM ISO may already be showing. There's several so if the first one doesn't work try another .
It's pretty rotten that the mfg of you computer is refusing to get u download media. They have the ISO's but refuse to help u out hoping you'll just upgrade to new one, thru them. Pretty stupid if u ask me.
There's the Windows ISO Downloader.exe tool from www.heidoc.net that can download a generic OEM iso, the only issue is there are a lot of people downloading the OEM's and a limited of downloads per month. Here's a link to a Microsoft answers thread with info about the tool. https://answers.microsoft.com/en-us/windows/forum/all/windows-7-oem-iso/867343f7-eded-4bc4-ac8b-4c03c2c16f04 you will have to scroll down to find the conversation. I linked the download tool at the beginning of this paragragh.
Just to clarify Microsoft make COEM's (Commericial OEM ISO's) which are a generic OEM iso. See this link - https://dellwindowsreinstallationguide.com/windows-7-8-1-and-10-direct-techbench-downloads/
Scroll down and you find this info -
COEM = Commerical OEM .isos are otherwise known as generic system builder .isos. These can be used with OEM keys on Windows 7 COAs affixed to your computer but requires phone activation. For a computer manufactured by Microsoft's largest OEMs such as
So your OEM key will work the COEM iso. Which is available with download tool above or go find one on the internet.
Edit - Found it on archive .org Win7_Pro_SP1_English_COEM_x64.iso