If an error on your vignette means you have not been issued with a BRP, you will need to report the problem immediately. This must be within three months of arriving in the UK, or before the expiry date on your vignette (whichever is sooner). It is extremely important to act promptly - an error on your vignette will impact both the documents you need to demonstrate your leave, and your ability to demonstrate the right to study on your programme. You will need to contact UKVI to report the error. Full details can be found here on the relevant gov.uk webpage.
Please note that UKVI are phasing out BRPs from 1st January 2025. This means that all BRPs have been issued with end dates of 31 December 2024 regardless of your actual length of Student permission. You will soon be able to prove your immigration status online without a BRP.
You will be required to create an online account in order to demonstrate your immigration status via an eVisa. Click here for more information and instructions on how to create an online account to access your eVisa.
In the meantime, you may be able to use the UKVI webpage to get a share code and get full details on the true length of your visa.