RSS Feed problem

I am attempting to send a Mailchimp RSS campaign when I add an event. However, at the moment, it seems to be sending every day, even if I haven’t added an event. Mailchimp says “Make sure your <pubDate> tags are set up and populating correctly. If a <pubDate> is set in another time zone or a day off, Mailchimp may not recognize that the items were posted before the next campaign is triggered”.

I notice when validating my feed that there is a <PubDate> for the feed but also for each event and that these are set in the future (i.e. the date of the event). validator.w3.org takes exception to this saying, “Implausible date: Sun, 27 Jan 2019 16:00:00 +0000 (10 occurrences)”. I wonder if Mailchimp is getting confused by this too?

Any way around this? Can I give Mailchimp a version of the feed that only has the <pubDate> tag for when the feed was updated?

Thanks in advance.

The page I need help with: [log in to see the link]