Best AI for customer service replies / head-to-head
Gemini 3.5 Flash vs GPT-5.6 Solfor customer service replies
GPT-5.6 Sol wins, 100–94
Same 12 customer service replies tasks, marked blind by three rival labs. GPT-5.6 Sol took 5 tasks, Gemini 3.5 Flash took 0, 7 tied. Tested 14 Aug 2026.
Where they differed most
A customer writes: 'Fix this today or I'm going to trading standards and every review site.' The complaint is legitimate (billed twice). Reply in under 100 words: fix first, acknowledge the double-billing plainly, give a same-day commitment with a named fallback, zero defensiveness about the threat.
I have just refunded the duplicate charge of [Amount] to your card. You were indeed billed twice for your order, and I am very sorry for this error. The refund has been processed on our end and should appear in your account today. If the funds are not visible by 5:00 PM, please contact me directly, or ask for our support lead, Sarah Jenkins, at [Phone/Email] so we can investigate with our bank immediately.
I’ve refunded the duplicate charge today. You were billed twice, and I’m sorry. You’ll receive refund confirmation by 5pm today. If it hasn’t arrived by then, our Billing Manager, Sarah Patel, will contact you directly today and complete the correction manually.
Task by task
| Task | Gemini 3.5 Flash | GPT-5.6 Sol |
|---|---|---|
| Refund the easy way | 10 | 10 |
| Say no without weasel words | 10 | 10 |
| Reply to a 1-star review | 10 | 10 |
| The confused customer | 9 | 10 |
| De-escalate a threat | 8 | 10 |
| The feature you won't build | 10 | 10 |
| Apologise for your mistake | 10 | 10 |
| Price rise notice | 10 | 10 |
| Outage update mid-incident | 9 | 10 |
| The wrong customer | 8 | 10 |
| Chargeback rebuttal facts | 10 | 10 |
| Refuse the fake review request | 9 | 10 |
Full receipts: Gemini 3.5 Flash, GPT-5.6 Sol · judges claude-sonnet-5, gpt-5.6-terra, grok-4.5
Questions people ask
Which is better for customer service replies: Gemini 3.5 Flash or GPT-5.6 Sol?
GPT-5.6 Sol — it scored 100/100 against 94/100 on our 12-task customer service replies suite, winning 5 tasks to 0 with 7 tied. Every answer was marked blind by three judges from three rival AI labs.
How was this tested?
Both models answered the identical published customer service replies tasks. Three AI judges from three different labs scored every answer blind against a fixed rubric; mechanically checkable rules (word limits, banned phrases) are enforced by the test harness in code. The raw outputs and judge verdicts are downloadable.
More customer service replies head-to-heads: GPT-5.5 vs GPT-5.6 Sol · GPT-5.3-Codex vs GPT-5.6 Sol · GPT-5.6 Sol vs Grok 4.5 · GPT-5.6 Sol vs GPT-5.6 Terra · Gemini 3.1 Pro Preview vs GPT-5.6 Sol · GPT-5.6 Sol vs Qwen3.7 Max
Full ranking: Best AI for customer service replies · model pages: Gemini 3.5 Flash, GPT-5.6 Sol