Klaviyo: Email Marketing & SMS

Good features in theory but terrible customer service. Good while they're trying to onboard you - with a phone call but no follow through afterwards. It's still opting subscribers in to mailchimp at two points and it automatically opts people in if they pay by paypal. I can't get any follow up help from my original contacts despite emailing several times. I've been trying to fix this for two months now and am no further on.