Sounds very like glow plugs. We had some fail on a Renault and the replacements were sent were the incorrect voltage (the system was set to 7v and they were 12v) so it was fine in summer but a nightmare come the cold weather. Fine when warm and a clod of white smoke when it eventually started. It was made worse on that car by the fact it was push button start and it would only crank the engine for a set time.
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