Describe what changed and what did not, using the same observation method where possible. Continuing symptoms need reassessment rather than an automatic assumption that the new part is defective.
What the observation tells you
A different thermometer position, new load or changed setting can make comparisons misleading. Equally, a genuine persistent problem should not be dismissed. Keep the invoice and the repairer's instructions so the discussion starts from the actual work performed.
A useful next step
Contact the repairer with a concise timeline, current settings and any warnings. Avoid fitting another speculative part or repeatedly resetting the appliance before they have reviewed the evidence.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.