Why won’t Dell let me a complaint?

I purchased a Dell laptop recently yesterday ordered some accessories that the website informed me would be delivered today.  I received an order confirmation today confirming the same.  Earlier today I received an email and text stating they would not be delivered until 7/10/25.  I am unable to be at home to receive then.  I spoke to Customer Support and was promise it would be escalated and I would be called back today.  I wasn’t.  However, 2 mins after the call I received an email telling me the order had been shipped and was expected to be delivered by 3/20/25 (today).  However, the tracking details showed 7/10/25.  I have 1) to speak to someone about this ( imposdible) , 2) emailed Support (no response) and 3) followed the instruction to register a complaint (does not open).  I am now stuck with no way of resolving this before the attempted delivery when I won’t be in to receive the items.  Firstly, the website terms have been broken under the Consumer Rights Act 2015 by stating a delivery date then changing it after the order was processed.  Secondly, Dell make it impossible to contact anyone to try and resolve this and not have proper Complaints procedure which again breaks the Consumer Rights Act 2015.  How can I get this resolved?