Clutch replaced at a main dealer now the transmission is failing.. related? on 2003 Kia Sedona

Less than one year ago (6000 miles) I had my clutch replaced at a main Kia dealership £800+ It made a funny noise from that point onwards not scary but just different I thought this was just the new clutch. However the noise got louder until I decided to take back to the garage to check. They said it's the transmission and it is failing and to open it up and repair could be £1500. The Kia has only done 74000 miles and has had main dealership services. I feel that the clutch and transmission failing are related ? How could I find out

Asked by for the 2003 Kia Sedona
should be under warranty,return for insp
The dealer said it's not related to the clutch replacement which is the question.
Can replacing a clutch on a sedona cause damage to the transmission if so how.
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