Every employee is given a one-time opt-out window when they’re first enrolled into a workplace pension scheme.
In your case, that window would have started when your employer initially enrolled you into the previous pension scheme. Even though your employer has now switched to Jarvis, that original opt-out window doesn’t reset with the change in provider.
But not to worry, you can ask your employer to stop your contributions.
To do this, you'll need to do the following:
Open the enrolment email you received from Jarvis
Click on the link that says 'Opt Out' or 'Cease Contributions'
A page will open up that says 'Request to cease pension contributions'
Click on 'Start Cease Request' and follow the process
Once you complete the process, this will send a notification to your employer who will action this for you.