You have exactly pinned the problem as you have been asking about upgrading within an existing infrastructure and that infrastructure will try and force you to stay within that infrastructure.
To give you as the user control over what you need you would need to order a new connection, not a transfer of an existing connection which leaves you in thrall to the existing infrastructure which will always have the incentive to keep you within the existing customer base and will try and produce reasons to make it hard for you to go elsewhere. There is no technological reason why two connections cannot exist in parallel but both supposed commercial necessities and the technology of the sign up processes within ISP web-sites mean that if you are out of the norm then you have problems.
If you are starting from scratch or wish to create a new connection before ceasing an existing connection none of those reasons will apply.
Edited by GonePostal (Wed 01-Oct-25 22:57:05)