Usually they would be bundled, but whether or not, the answer is there is no problem. So far as Ofcom are concerned.
Take the example of Plusnet, or even BT, with the opposite situation. Broadband price rises, line is on LRS. Both ISPs used to allow leaving without penalty on the broadband, but refused to refund the LRS outstanding. Both have now changed their tune after an Ofcom ruling.
It's been discussed very recently in the Plusnet forum
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