If this took place upon their agreement at the time of the contract, this is not permissible as it is a way leading to Riba (usury), which is
selling coffee to be paid for by food at a delayed time. This is known as Riba Al-Nasi'ah (usury of delay, conditional excess for delay of payment).However, if they did not agree to that at the time of the sale and this is easier for them, there is no harm in that, since there is no means to Riba.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.